Both Islam and Christianity are Abrahamic religions.
The definition of a Christian varies among different Christians groups. Roman Catholics, Protestants and Eastern Orthodox define Christians as a one who is the member of the Church and the one who enters through the sacrament of baptism. Infants and adults who are baptized are considered as Christians. Jesus’ Jewish group became labeled ‘Christian’ because his followers claimed he was ‘Christ’ the Greek equivalent of the Hebrew and Aramaic word, ‘Messiah.’
Islam (Arabic: الإسلام; al-'islām (help•info)) is a monotheistic religion originating with the teachings of Muhammad, a 7th century Arab religious and political figure. The word Islam means "submission", or the total surrender of oneself to God (Arabic: الله, Allāh). An adherent of Islam is known as a Muslim meaning “one who submits to God”.
The first known usage of the term Christians can be found in the New Testament of the Bible. The term was thus first used to denote those known or perceived to be disciples of Jesus. Similarly, in the two other New Testament it refers to the public identity of those who follow Jesus. The history of early Christian groups is told in Acts in the New Testament. The early days of Christianity witnessed the desert Fathers in Egypt, sects of hermits and Gnostic ascetics. Christianity began in 1st century AD Jerusalem as a Jewish sect but spread throughout the Roman Empire and beyond to countries such as Ethiopia, Armenia, Georgia, Assyria, Iran, India, and China.
Islam's historical development resulted in major political, economic, and military effects inside and outside the Islamic world. Within a century of Muhammad's first recitations of the Qur'an, an Islamic empire stretched from the Atlantic Ocean in the west to Central Asia in the east. Muhammad began preaching Islam at Mecca before migrating to Medina, from where he united the tribes of Arabia into a singular Arab Muslim religious polity. With Muhammad's death in 632, disagreement broke out over who would succeed him as leader of the Muslim community. Many leaders followed. For the Umayyad aristocracy, Islam was viewed as a religion for Arabs only. Islam spread rapidly during 750-1258 the era that they call The Golden Age. Since then this religion has progressed by leaps and bounds across the world.
The Christian Religion encompasses all churches as well as believers without churches, as many modern practitioners may be believers in Christ but not active church goers. A Christian will study the Bible, attend church, seek ways to introduce the teachings of Jesus into his or her life, and engage in prayer. A Christian seeks forgiveness for his or her personal sins through faith in Jesus Christ. The goal of the Christian is both the manifestation of the Kingdom of God on Earth and the attainment of Heaven in the after-life.
Muslims believe that God revealed the Qur'an to Muhammad, God's final prophet, and regard the Qur'an and the Sunnah (words and deeds of Muhammad) as the fundamental sources of Islam. They do not regard Muhammad as the founder of a new religion, but as the restorer of the original monotheistic faith of Abraham, Moses, Jesus, and other prophets. Islamic tradition holds that Judaism and Christianity distorted the messages of these prophets over time either in interpretation, in text, or both.
Christianity regards the Holy Bible, a collection of canonical books in two parts (the Old Testament and the New Testament) as authoritative: written by human authors under the inspiration of the Holy Spirit, and therefore the inerrant Word of God.
The principle scriptures of Islam are the Quran and the Hadith. The Quran is the source of Allah's revelations to humanity, transmitted through his messenger, Muhammad. The Hadith is not considered a direct source of revelation; instead, it is supposed to contain the records of the traditions, practices and decision of the very earliest Muslim community.
Christians believe that all people should strive to follow Christ's commands and example in their everyday actions. For many, this includes obedience to the Ten Commandments. Other Christian practices include acts of piety such as prayer and Bible reading. Christians assemble for communal worship on Sunday, the day of the resurrection, though other liturgical practices often occur outside this setting. Scripture readings are drawn from the Old and New Testaments, but especially the Gospels.
Islam includes many religious practices. Adherents are generally required to observe the Five Pillars of Islam, which are five duties that unite Muslims into a community. In addition to the Five Pillars, Islamic law (sharia) has developed a tradition of rulings that touch on virtually all aspects of life and society. This tradition encompasses everything from practical matters like dietary laws and banking to warfare.
The Holy Quran is the highest authority in Islam. It contains the exact words of God as revealed to Prophet Muhammad and recorded by his companions. The basis faith teachings of Islam preach about the divinity and supreme authority of God(Allah). It also preaches tolerance towards other religions. Only Islam has questioned the basic tenets of Christianity, such as the Trinity, the divinity of Jesus and his atoning death on the cross. Islam does not approve the use of force in the propagation of religion. For Muslims, the Quran answers questions about daily needs, both spiritual and material. It discusses God and God's Names and attributes; believers and their virtues, and the fate of non-believers (kâfir); Mary, Jesus, and all the other prophets; and even scientific subjects. In practice, the laws that Muslims follow are contained in the law collections known as the Hadith. Islam also teaches respect towards parents and elders. Christianity, on the other hand preaches the trinity of God and the existence of God(Jesus) as immortal. Christianity talks about Jesus as the saviour of the world and doesn't regard Islamic principles as true. Another universal teaching of Christianity is following the concept of family values, helping the powerless and promoting peace.
There are many people who follow Christianity and have divided themselves into various groups/ sects depending upon varying beliefs. The types of Christians include Catholic, Protestant, Anglican, Lutheran, Presbyterian, Baptist, Episcopalian, Greek Orthodox, Russian Orthodox, Coptic, Rastafarian, Gnostic. Almost all Muslims belong to one of two major denominations, the Sunni and Shia.
Data suggests that there are around one billion and eight hundred million Christians in the world. There are around 1.1 to 1.8 billion Muslims in the world, making Islam the second largest religion n the world after Christianity.
Commonly cited estimates of the Muslim population in 2007 range from 1.1 billion to 1.8 billion. Approximately 85% are Sunni and 15% are Shia, with a small minority belonging to other sects. Some 30–40 countries are Muslim-majority, and Arabs account for around 20% of all Muslims worldwide. South Asia and Southeast Asia contain the most populous Muslim countries, with Indonesia, India, Pakistan, and Bangladesh having more than 100 million adherents each.
Christianity is the world's largest religion. It is the predominant religion in Europe, the Americas, Southern Africa, the Philippines and Oceania. It is also growing rapidly in Africa and Asia, particularly in China, South Korea and the Middle East. It is declining in other countries including Australia, Great Britain, France and Germany.
For further reading, there are several books available on Amazon.com on Islam and Christianity: